Electric door operator



July 11, 1939. E. G. PARVlN ELECTRIC DOOR OPERATOR Filed Dec. 30, 1957INVENTOR. Edward G. Parvm BY %Jr3mu ATTORNEYS firmed July 11, 1939UNITED STATES PATENT OFFICE National Pneunatic Company,

Virginia a corporation of West Railway, N. 1.,

Application December :0, 1931. Serial No. 182.38.) 1: Claims. (Cl.172-239) This invention relates broadly to improvements in electric dooroperating apparatus particularly of the type in which the door travel isrelatively small and the door is cushioned in its movement 5 at theendof its stroke in either direction.

A broad object of this invention is to provide an improved form ofelectric door operator which insures the smooth rapid opening andclosing of a door with a cushioning action at the end of its opening andclosing strokes.

A more specific object of the invention is to provide, in cbmbinationwith an electric motor door operator of a retarding device connectedthereto whereby the motor is brought to a maximum speed of operationquickly so that such a condition is attained before the door is fullyopened or fully closed and indeed before the door reaches the cushioningzone in either direction of movement.

A further object of this invention is to provide a control system for anapparatus of this type in which the retarding means, which iselectromagnetic, is maintained energized in full open and full doorclosed position to hold the doorthereat.

Other and more specific objects of this invention which are successfullysecured by means of the mechanism herein disclosed will become apparenthereinafter.

This invention resides substantially in the combination, construction,arrangement and relative location of parts, all as will be detailedbelow. 7

In the accompanying drawing, the single figure diagrammaticallyillustrates a combination 'employing the invention herein.

The operation of doors, such as those found on vehicles, as for examplethe doorsof buses,

. street cars, subway trains, elevator cars and'the like, by means of amotive device, is not a simple thing to accomplish satisfactorily undermodern requirements often encountered. For example, an elevator door ofnecessity has mechanism connected thereto which involves springresistance to the opening movement of the door re- 45 quirlng a somewhatstronger motor than would benecessary to operate the door itself. On theother hand, during the closing movement this very spring mechanisminstead of resisting movement of the door is aiding it which, in conjunc50 tion with a motor which is now stronger than necessary to clos .thedoor, causesan unduly rapid movement thereof. In part, because of theseconditions it is desirable, to cushion or retard the door in itsmovement near the end of its stroke in either direction so that it ismore or less gradually brought to rest at the extreme open and closedpositions.

Furthermore, in the motor operation of doors, such for example aselevator doors, and particularly when electric motors are employed, theshortness of the door stroke. is such that the door in either directionof movement reaches the cushioning zone before the electric motoroperator has attained maximum speed. The result is that upon reachingthe cushioning zone the door must begin to slow down at the time themotor is still accelerating. Of course this involves a very suddenchange in conditions which are undesirable for many obvious reasons.

An important object of this invention is to provide a braking orretarding means connected to the electric motor which, in effect,considerably lowers the maximum operating speed of the motor so'that themotor, in combination therewith, very much more quickly reaches thislower speed and before the door reaches the cushioning zone. It follows,therefore, that the motor now decelerates not from an acceleratingcondition,

but from an attained stable condition.

Referring to the drawing, there is shown a three-phase power supplycircuit including the wires A, B, and C. Connected across one phase ofthis circuit, as for example the wires B and C, are the branch circuitwires BI and Cl which are connected, in paralleLto the primaries of apair of transformers T. The secondary T is connected to the currentsupply-wires I, and 2.

-'Ihe voltage of the circuit comprising the wires I and 2 may, forexample, be of the order of volts and the voltage of the polyphasecircuit maybe of the order of 220 volts representing conditions normallyencountered in this art.

The secondary T" is connected to the input of l a suitable rectifier R.The particular type of rectifier employed is of no importance per sealthough it may be noted that the copper oxide type is practical. Theoutput of the rectifier is connected to the direct current voltagecircuit wires 3 and 4.

At 1 0, C and RC are diagrammatically illustrated the operating windingsof relay switches which are connected as shown across the circuit wiresI and 2. The relaywinding I operates the contacts II, 12, I3 and 14 ofwhich the contacts II and 13 are normally open switches while thecontacts 12 and I4 are-normally closed switches, when the winding I isdeenergized. The relay winding 0 controls the contacts Olwhich arenormally open switches when the winding is deenergized. The relaywinding C controls the contacts Cl and are normally open switches whenthe winding is deenergized. The relay winding RC controls the contactsRCI which are normally .open switches when the winding is deenergized.The contacts CS are the door control contacts which are commonlyincorporated in the elevator car controller and controlled manually bythe car operator, or automatically in automatic systems. The switchcomprising these contacts is open when the door is closed and is closedto open the door. It will be seen that the contacts CS are in serieswith the winding I. The contacts II are in series with the winding and aswitch OLS while the winding C is in series with the cont acts I2 and aswitch CLS. The three circuits of the windings 1,0 and C are in serieswith contacts OLI.

The contacts OLS and C13 represent well known types of door limitswitches which are arranged to be operated by the door. The contacts OLSare normally closed, as indicated, when the door is closed and thecontacts CLS are normally open when the door is closed. When the door iscompletely open switch OLS opens and switch CLS closes as soon as thedoor starts to open, the former condition being restored when the doorstarts to close and is closed.

The contacts 0| and Cl are in the three-phase circuits to the motor Mand are employed in the manner illustrated and well known to providereversing means whereby when the switches OI are closed the motor isenergized in a direction to open the door and when the switches Cl areclosed the motor is energized in the reverse direction to close thedoor. The circuits to the'motor are completed through the resistors MRwhen the switches RCI are opened, but are partlyshortcircuited whenthese switches are closed. In accordance with common practice, thecircuit to the motor is completed through the overload re-.

lay winding OL, which, when energized, opens the normally closedcontacts OLl. v

Returning now to the direct current circuit, there is shown a winding BWwhich is the energizing winding of theretarding or braking mechanism.This winding is connected in series from the wire 4 to the wire 3through a resistance OCR, a relay operating winding BSR and in seriesthrough either the resistor OR or the resistor CR. The contacts orswitchesIS and 14 are in series,respectively, with these resistors. Adoor operated switch S is provided with two pairs of fixed contacts 5, 6and 1, 8 and a movable contact A. This switch is shown in the drawing indoor closed position where the contact A interconnects the contacts and6. As shown, the contacts 5 and 1 are connected by the common lead fromthe winding BW to the resistors OR and CR which lead is also connectedby adjustable contacts with the resistors. The contacts '6 and 8 are,respectively, connected to the ends of the resistors CR and OR. Therelay winding BSR controls the contacts BSRI which form a switch inseries with the winding RC. This relay is of a type which re-' quiresfull energization of its winding to open its contacts, partialenergization not being suflicient to hold them open.

I induction motor having a stator and a rotor whose shaft is common withthe rotor shaft of the motor M. The winding BW represents the field orstator winding of the brake. Such a combination is known in the art andone form is shown in detail in my copending application Serial No.115,176 filed December 10, 1936. The operation of this apparatus willnow be given in detail. It is first to be noted that the mechanismdiagrammatically illustrated is shown in door closed position at whichtime the switch CS is open. At this time the switch 12 is closed but thewinding C is not energized because the limit switch CLS is open.However, the brake winding BW is energized from wire 3 through resistorOCR,.relay winding BSR, switch I4, contact 8, contact A, contact 5 andthrough the winding BW to the wire 4. It will be seen that the re-vsistor CR is short-circuited so that the full current is on the brakewinding so that the brake is fully applied to hold the door closed. Theenergization of the winding BSR keeps the switch BSRI open so that thewinding RC is deenergizedand the contacts RCI are open. The result isthat all of the resistances MR are in circuit with the motor M. However,the motor is not energized because relay winding 0 is deenergized andswitches OI are open and, of course, the same is true of winding C andswitches Cl.

To open the doors switch CS is closed energizing the winding I from wireI through switch CS and overload relay switch OLI .to wire 2.Energization of the winding I causes the closing of switches II and I3and the opening of switches 12 and 14. The closing of switch II causesthe energization of winding 0 which closes the switches OI supplyingcurrent to the motor M. The switch I4, upon energization. of the winding1 opens so that the current to winding BSR is supplied through resistorOR but is of such small value that the switch BSRI closes. Thereuponwinding RC is energized closing switches RCI so as to short outportionsof the resistors MR so that the motor is operating at full power. Ofcourse thoseskilled in the art will readily see that this all occurssimultaneously so that the full power is put on the motor about as soonas the switch CS is closed.

. At this time the brake winding BW is energized from the wire 3 throughresistor OCR, winding BSR, switch 13, all of resistance OR adjusted incircuit for'use to the winding BW and wire 4. It will be recalled thatthe brake is connected to the motor and a partial energization of thewinding BW causes the brake to resist the 'motor so that it is quicklybrought up to the maximum cushioning zone. The door switch S is adjustedso that just as the door reaches the cushioning zone as it opens, thecontact A interconnects contacts I and I. The result of this is that allof resistance OR- is short-circuited and the current flowsdirectly fromthe windingBSR through the contacts I, A and I, to'the brake winding BWincreasing the energization thereof and acting to retard the door;motor.

At the time of this current increase the energization of the winding BSRbecomes high enough so that contacts BSRI open. Winding RC isdeenergized through these contacts, opening the switches ROI and cuttingthe rest of the resistance MR into the circuit so that the motorcontinues to move the door to full open position at reduced power. Thusit will be seen that at the time the motor M is operating at reducedpower the brake winding BW is fully energized and is operated at maximumpower. Just as the door reaches full open position limit switch 018opens,

limit switch CLS having closed as soon as thedoor started to open. Theopening of switch OLS deenergizes the winding so that the switches OIopen and the motor comes to a stop. It will be noted, however, that thewinding BW remains fully energized, holding the door in open position.The closing of switch CLS prepares the circuit to relay 0 for closingwhen the switch I: closes. Switch It does not close, however, until theswitch CS is opened, deenergizing the winding I which is not done untilthe operator is ready to close the doors.

In order to close the door the operator opens the switch CS,deenergizing winding I with the result that contacts II and 13 open andcontacts 12 and-,1! close. The closing of contacts 12 energizes windingC which closes the switches CI, reversely energizing the motor M. Atthis time the switches RCI are closed shorting out most of theresistances MR sothat the motor M is operating at full power. Theseswitches are closed because winding RC is energized through the closedcontacts BSRI which are closed because the current reaching the windingBSR through adjusted resistance CR is reduced. Under these, .conditionsthe door is operated at full power until it approaches the cushioningzone in the closing direction at whichtime the switch 8 is shifted fromthe position previously assumed back'to the position shown in thedrawing where contact A interconnects contacts I and 6. As soon as thishappens, the resistance OR is shortcircuited and the current through'thewinding BSR increases so thatthe contacts BSRI open,

deenergizing relay RC and opening contacts RCI. At the time the currentin the winding B88 in-' creased to -full value it of course alsoincreased to fullvalu'ein the brake winding BW. The opening of contactsRCI takes the short circuit of! the resistance MR so that the door motorslows down but continues to operate at reduced power until the door isfully closed, at which time switch 0L5 closes. ,Switch CLS opens as soonas the door starts to close. The opening of switch 018, ofcourse,,deenergizes the winding C so that the contacts Cl open and themotor :through.

The resistance'OCR is adjustable so as to ad- .just the retarding eifectof the brake during the cushioning portion of the movementof the I doorand hence may he stated to be adjustable to give any desired cushioningeifect. The resistances OR and CR are adjustable and control the openingand closing speeds of the door. The resistances MR in the motorcircuitare adjustable to vary the power delivered by the motor; Inadjusting all of these resistances it may be stated that they are alladjusted so that the door will move slowly and open the limit switcheswhen relay RC is deenergized. These resistances willneedtobeadjustedfrom timetotime as the parts wear and the temperaturechanges in order to maintain a desired operating condition. The lengthof the cushioning zones may load; killing all the circuits connectedtherebe readily varied by adjusting the switch 8 so as to be operated bythe door or some other part of the equipment operating in timed relationtherewith at diiierent points in the door travel. As is obvious to thoseskilled in the art, the length'of -the cushioning zone may. be varied bythe proper adjustments of the switch 8 or, in other words, the equipmentmay be adapted to operation of doors having diilerent distances oftravel.

It is likewise clear that the limit switches 0L8 and ('JLS need not beoperated directly by the door but by some part of the mechanism movingintimedrelation therewith. Thus. for example, these two switches andindeed the switch 8 may be operated by the motor itself in accordancewith well known principles in the art.

The above description will be apparent to those skilled in the art butthe details comprising the combination herein disclosed may bevariedwithout departure from the novel scope of the subject matter hereof. Ido not,therefore, desire to be strictly limited to the disclosure asgiven for purposes of illustration, but rather to the scope of theclaims granted me.

What I seek to secure by United States Letters Patent is:

1. A motor control system including an electric motor, a magnetic brakeconnected to said motor to resist operation thereof, an energizingcircuit 1 for said motor, control means for connecting said motor tosaid circuit, connections from said circuit to, maintain the brakecontinuously applied when the: system is in operation, and meanscontrolled by said control means for reducing the force of applicationof said brake when the motor is energized.

2. A motor control system including a reversible.

means for reducing the force of application of motor to said circuit,connections from said circult to maintain the brake applied when themotor is energized and deenergized, means controlled by said controlmeans for reducing the force of application of said brake when the.motor is energized, and means operated by said motor for reducing thespeed thereof at the end'of a predetermined period of time. 7

4. .A motor control system including an electric motor, a magnetic brakeconnected to said motor to resist operationthereof, an energizingcircuit for said motor, control means for connecting said motor to saidcircuit, connections from said circult to maintain the brake appliedwhen the motor is energized and deenergized, means controlleds-by saidcontrol means for reducing the force of application of said brake whenthe motor is energized, means operated by said motor for reducing thespeed thereof at the end of a predetermined period of time andincreasing they force of application of said brake.

ble electric motor, a magnetic brake connected to said motor to resistoperation thereof in either direction, an energizing circuit for saidmotor,

control means for selectively connecting said motor to said circuit fordirect or reverse opera-' tion, connections from said circuit formaintaining the brake applied when the motor is energized anddeenergized, means controlled by said control means for reducing theforce of applicamotor to said circuit for direct or reverse operation,connections from said circuit for maintaining the brake applied when themotor is energized and deenergized, means controlled 'by said controlmeans for reducing the force of application of said brake when the motoris energized for operation in either direction, and means operated bythe motor for partially reducing its speed for either direction ofoperation at the end of a predetermined period of time and increasingthe force of application of said brake.

7. A motor control system including a reversible electric motor, amagnetic brake for said motor having-an energizing winding, anenergizing circuit for said motor, connections including resistance formaintaining the brake energized when the motor is at rest, means forreversibly connecting said motor to said circuit, means for connectingadditional resistance into the brake winding circuit when the motor isenergized for operation'in either directi0n,and means operated with saidmotor for cutting said additional resistance out of circuit to increasethe energization of the brake winding at the end of a predeterminedperiod of time.

8. A motor control system including a reversible electricmotor, amagnetic brake for said motor having an energizing winding, anenergizing circuit for said motor, connections including resistance formaintaining the brake energized when the motor is at rest, means forreversibly connecting said motor to said circuit, means for connectingadditional'resistance into the brake winding circuit when the motor isenergized for operation in either direction, means operated with saidmotor for cutting said additional resistance out of circuit to increase.the energization of the brake winding at the end of a predeterminedperiod of time, and means including resistances in the motor circuit andcontrolled by said last mentioned means for cutting the motorresistances into circuit at the same time.

9. In a motor controlled system theeombination including an electricmotor, an energizing circuit for said motor including a switch andresistance, a brake for resisting operation of said motor, connectionsfrom said circuit to said brake for maintaining it energized, manuallycontrolled means for operating said switch, means simultaneouslyoperated for reducing, the energization of the brake when said switch isclosed, and means operated with the motor for increasing the resistancein the motor circuit and the energization of the brake at the end of apredetermined period of time.

10. A motor control system including an electric motor, a magnetic brakeconnected to said motorto resist operation thereof, an energizingcircuitfor said motor, control means for connecting said motor to saidcircuit, connections from said circuit to maintain the brake energizedwhether the motor is energized or deenergized, means controlled by saidcontrol means for reducing the energization of said brake when the motoris energized, means operated with the motor for increasing theenergization of the brake at the end of a predetermined period of timeand means operated by the motor fordeenergizing it at the end of apredetermined period of time.

11. A motor control system including an electric motor, a magnetic brakeconnected to said motor to resist operation thereof, an energizingcircuit for said motor, control means for connecting said motor to saidcircuit, connections from said circuit to maintain the brake energizedwhen 'the motor is at rest, means controlled by said control means forpartially reducing the energization of said brake when the motor isenergized, and means operated with the motor for increasing the brakeene'rgization and decreasing the motor energization at the end of apredetermined period of time.

12. A motor control system including an electric motor, a magnetic brakeconnected to said motor to resist operation thereof, an energizingcircuit for said motor, control means for connecting said motor to saidcircuit, connections from said circuit to maintain the brake energizedwhen the motor is at rest, means controlled by said control means forpartially reducing the energization of the brake when the motor isenergized, means operated with the motor for increasing the brakeenergization at the end of a predetermined period of time, and meansoperated by the motor for deenergizing it at a desired time. i

13. A motor control system including a reversible electric motor, amagnetic brake for said motor having an energizing winding, anenergizing circuit for said motor, connections for maintaining the brakeenergized at all times while the system is in use, means for reversiblyconnecting said motor to said circuit, and means for connectingresistance into the brake winding circuit when the motor is energizedfor operation in either direction.

- EDWARD G. PARVIN.

